Hey y'all,

I am looking for a switch in which I can turn a relay on and off when power is applied (i.e. DC battery pack), but when the DC battery pack is removed it resets the relay and the switch to off. Also when the battery pack is applied again both remain off until the switch turns it on. Has anyone ran into such a switch? A link would be greatly appreciates thanks everyone.

 

Have a look at the following link for the latching relay.

http://www.google.co.uk/imgres?imgu...mage_result&resnum=6&ct=image&ved=0CDIQ9QEwBQ

 

SCR is what you may want.

When an SCR gets power to the gate, it latches. Power can flow to your relay coil doing what you want. It will not turn off until power is removed.

When power is re-applied, the SCR will be off, until you apply power to the gate again.

Here is some info in our eBook:
http://www.allaboutcircuits.com/vol_3/chpt_7/5.html